Traditionally, most data center or telecom networking enclosures use either “90-degree turned front-to-back” or “side-to-side” airflow to cool the internal line card components. The “90-degree turned front-to-back” airflow design requires a dedicated air inlet area which is usually located on the lower front area of the enclosure. Once the air enters through this lower air intake, it needs to turn 90-degree up to go through all the vertically oriented line cards and the warm air finally exits through the rear exhaust area. The slightly simpler “side-to-side” airflow design requires perforation on both side walls of the enclosure as all line cards are placed in horizontal orientation. A fan tray is placed on one side of the enclosure to either blow or suck the air through the line cards to cool them.
In order to meet the air filtration requirement which is part of the stringent NEBS (Network Equipment Building System) industry standard, a removable foam filter is attached to the air inlet area of the enclosure. For the “90-degree turned front-to-back” enclosure design, a filter is attached on the bottom air intake area. For the “side-to-side” airflow enclosure design, a filter is attached to the side air intake area on the enclosure wall. Because the filter is placed well away from the busy line card area, it does not interfere with the line card operation or the network cable management that needs to be plugged to the line card's input/output ports. However, some of latest data center enclosures are now using the new airflow architecture design called “straight front-to-back” for the air to enter straight through the perforated line card face plates and exit through the rear fan trays. One of the key advantages of this design is that no valuable vertical or side rack space are wasted to provide the empty air baffling space for the air to turn or redirect. Still, this presents a challenge for the NEBS air filtration requirement since the entire front area of the enclosure now needs to be sealed with filters to keep dust out while still allowing the outside cables to be plugged into the line cards.